The demand for pine trees to make wood products continues to increase. One proposed solution to this problem is to identify individual trees that possess desirable characteristics, such as a rapid rate of growth, and produce numerous, genetically identical, clones of the superior trees by somatic cloning. These clones can be cultivated to yield stands, or whole forests, of pine trees that possess the desirable characteristic(s).
One method for cloning pine trees utilizes in vitro treatment of isolated, living, pine tissue under conditions that promote formation of pine embryos, and then whole plants, from the treated tissue. The isolated pine tissue may be cultured in the presence of one or more auxins and/or cytokinins to promote formation and multiplication of embryogenic tissue to form cotyledonary pine embryos. The embryos may then be germinated and grown to yield pine trees.
A continuing problem, however, is stimulating efficient formation of cotyledonary pine embryos that are capable of germinating to yield pine plants. Preferably the cotyledonary pine embryos, formed in vitro, are physically and physiologically similar, or identical, to zygotic pine embryos formed, in vivo, in pine seeds. There is therefore a need for methods for producing cotyledonary pine embryos from pine embryogenic tissue. The present invention provides methods that satisfy this need.